Field
The present specification generally relates to the field of photovoltaic power generation and, in particular, to a tracking control system for photovoltaic power generation devices.
Technical Background
Solar photovoltaic power generation refers to a technology in which the incident sunlight is received by an array formed by solar photovoltaic module subsystems, converted into electric energy through photovoltaic conversion, and the generated electric energy is collected for use. This technology has the advantages of pollution-free, inexpensive and sustainable power generation, and it is increasingly applied in the tropical or desert regions around the world in which the sunshine conditions are strong.
At present, in the solar photovoltaic power generation system, a large number of assemblies for photovoltaic module subsystems are typically disposed on an open area (or on a surface of a building roof that is directed exposed to sunlight), and on the assemblies, photovoltaic panels are mounted by which the sunlight irradiation is received photovoltaic power generation conversion occurs. In general, according to the terrain of the deployment area, the number of the sets of assemblies can be more than ten, dozens of groups, hundreds of groups or even thousands of groups. Meanwhile, in order to make the photovoltaic module subsystem receive the sunlight better, a solar tracking system for photovoltaic module subsystem has been implemented in the art. By tracking the motions of the sun in real-time and adjusting the orientations of the assemblies of the photovoltaic module subsystem, a perpendicular incidence of sunlight onto the light-receiving plane of the photovoltaic module subsystem is achieved, the amount of solar radiation received by the photovoltaic module subsystem can be increased, and the total amount of power generated by the solar photovoltaic power generation system can be raised.
In brief, the implementation principle of an automatic tracking system for the photovoltaic power generation device is mounting a tracking sensor on the assembly on which the photovoltaic module subsystem is mounted. When the direction of the light changes, the tracking sensor outputs an offset signal, the tracking system starts to operate, adjusts the orientations of the photovoltaic module subsystems on the assemblies until the tracking sensor reaches a balanced state again (i.e. the light-receiving plane of the photovoltaic module subsystem is perpendicular to the incident sunlight), stops the operation, and completes one adjustment. By such continuous adjustment in real-time, it can be ensured that the photovoltaic array module subsystems follow the sun along the traveling tracks of the sun at any time, raising the total amount of generated power. The automatic tracking system can be equipped with a circuit for resisting stray light interference and for night tracking, and equipped with a manual control switch to facilitate the configuration.
The traditional automatic tracking methods for a photovoltaic power generation device generally include: horizontal single-axis automatic tracking, tilt single-axis automatic tracking and two-axis tracking, etc. However, at present, these tracking methods typically implement one control device for one assembly, that is, a single controlling and driving system is used to control a single assembly of a photovoltaic module subsystem. If it comes to a large-scale deployment on a large area, then it requires the number of controlling and driving systems equals to the number of the photovoltaic module subsystems, which substantially increases the deployment costs and deployment difficulties, and is unfavorable for the widely-spread utilization of photovoltaic power generation in under-developed areas. Hence, there is a need for a centralized tracking control system for multiple assemblies of photovoltaic module subsystems.
Due to the daily motion of the sun from east to west, all the tracking systems in the prior art will automatically adjust the orientation according to the motion of the sun. Conventional single-axis systems track the sun motion by fixedly placing themselves in the south-north direction, and adjust and rotate in the east-west direction to track the sun. However, such placement is not the most efficient scheme. Specifically, the central axis of the assembly of the photovoltaic module subsystem has to be placed in south-north direction, and the entire assembly may rotate around its central axis, thereby realizing a deflection of the panel of the photovoltaic module subsystem towards east or west, so as to receive the sunlight better. However, for some areas, due to reasons such as non-horizontal deploying terrains and cloud cover in the sky, even if the assembly is adjustable in the east-west direction, it is still unable to adjust the panel of the photovoltaic module subsystem to be perpendicular to the incident direction of maximal optic axis in case of fixing the assembly in the south-north direction. Therefore, there is also a need for a two-axis tracking system for the photovoltaic module subsystem that is adjustable in both the east-west and the south-north directions.
Meanwhile, for the photovoltaic module subsystems at present, wind resistance is also an important factor to be considered. There are a lot of sunlight and typhoons in southern China, wherein the assembly of the photovoltaic module is exposed to strong winds, and will undergo winds from all directions. The winds will impose lateral and longitudinal pressures on the assembly. This puts high requirements on the wind resistance of the assembly. When skewed by the wind, the weight of the photovoltaic module itself will be sufficient to deviate the center of gravity of the whole assembly, and then make it collapse. Hence, there is a need for an assembly for the photovoltaic module that has good wind resistance.
On the basis of the above requirements, in the field of photovoltaic power generation so far, there is a lack of a tracking system for photovoltaic module which provides tracking control for multiple assemblies of the photovoltaic modules in a centralized manner, can be deployed in large areas on various terrains, and has good wind resistance.